How do I get my older female cat, and young male cat to get on? At the end of my tether!?

I have a ten year old female cat who I have had from a kitten. About 4 months ago, I was rescued a tomcat, who is now a year old. while they werent the best of friends, they got on okay. while waiting to have him netuered, he had two days where he attacked my other cat, and it was quite nasty. the older cat wet herself. We had to separate them. and he kept spraying everywhere. Hes come back from his operation today, a little sudued, but now my female cat keeps hissing at him, and just wet on our bed, although he has made no attempt to attack her. Any advice would be very much appreciated. They got on fine before, but now our house seems like a war zone. Any ideas would be great. The older cat isn't much for treats or playing with toys, she is more of a sleeper and eater, so the usual reinforcing with treats i feel may not work.